Who understands the principle of pilot-operated pressure relief valves?
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I spent a long time looking at it but still didn’t understand how the pressure coming in from the pilot could push open the main valve disc; from the perspective of force balance, it’s impossible for this valve to open
Above is the pilot pressure F1, below is the material pressure F2 plus the upward force of the main spring F3, where F1
The pilot force balances the medium pressure, and the regulating pressure only overcomes the spring force.
It was clearly explained on the 7th floor; I’ve learned it.
I think the inlet of this pilot pressure reducing valve should be the port on the right, while the outlet is the port on the left. It can be pushed open because the cross-sectional area of 10 is much larger than that of the main valve’s spool, which allows it to overcome the upward force exerted by the spring below
However, it is not. It seems you have the same question: the main valve must be lowered in order to open it, but how can it be opened when the spring is constantly pushing against it?
What I’m referring to is the downward force applied to the main valve; the high-pressure fluid on the right side first pushes down on the pilot valve 6, thereby connecting the flow channel on the right side of the pilot valve 6 with the inlet. The high-pressure fluid from the inlet enters the cavity above 10, and through hydraulic pressure, 10 moves downward, thus opening the main valve. When the inlet pressure is low, the lower spring pushes up on the main valve, connecting the outlet flow channel with 10, allowing pressure to be released from the interior of 10 and causing the valve to close partially
The area of the 10-piston is much larger than that of the 13-valve core; when the pressure of the incoming medium enters the upper chamber of the piston through the pilot valve, it opens the valve core. Once an outlet pressure is established, it acts on the piston to gradually close the valve core, thereby achieving equilibrium.